The invention relates to a latch needle that may be used in textile machines. Such textile machines are, for example, circular knitting machines, flat-bed knitting machines or hosiery machines.
A latch needle, as has basically been known from publication DE 36 00 621 C1, has a base body with an end-side hook. The base body is provided with a latch slot in the vicinity of the hook. One end of a latch that is disposed for opening and closing the hook projects into the latch slot. A latch hole is provided on one end of the latch, where a swivel pin extends through said latch hole. The latch slot is delimited by two slot walls. A wall hole is provided in each slot wall. Both wall holes are in alignment with each other. The swivel pin extends through the latch hole and is held by its ends in the wall holes. The outside edges of the two wall holes are deformed radially inward so that the swivel pin is held firmly in place in its axial direction.
Considering this solution, the latch hole of the latch is pivotally supported on the stationary swivel pin. Here, any potential wear of the bearing is concentrated on relatively small surfaces.
Similar solutions have been known from German Patent 14407 and publication DE 36 0692 A1.
German Patent 917243 and German Auslegeschrift 1906892 disclose latch needles with a co-rotating swivel pin. In so doing, DE 917243, FIG. 2, provides a latch hole that has a smaller diameter than the wall holes. The swivel pin consists of plastic material and has a diameter greater than the latch hole, however, a diameter smaller than the wall holes. If said swivel pin is drawn into the latch hole with appropriate force, said pin will be seated in said hole in a force-fit manner. The ends of the swivel pin that project from the latch are rotatably supported in the wall holes.
As opposed to this, DE 1906892 is based on a swivel pin of steel. Again, the latch hole has a smaller diameter than the wall holes. The swivel pin that is inserted in the latch hole is axially upset, so that it is seated in the latch hole in a force-fit manner. The ends projecting from the latch hole form rivet heads having the form of a truncated cone, said rivet heads being rotatably supported in the wall holes.
Whereas the aforementioned publications basically assume the use of swivel pins having essentially two equally configured ends, DE 35 45 037 C2 provides a swivel pin that is arranged asymmetrically with respect to the latch. In this case, only one slot wall is provided with a wall hole that receives the swivel pin. The oppositely arranged slot wall does not have a wall hole. The front side of the swivel pin abuts against this slot wall. Again, the latch is rotatably supported by the round swivel pin.
To the extent that the aforementioned solutions relate to swivel pins that co-rotate with the latch, said solutions are based on a force fit between the latch and the swivel pin. Considering mass production, the precise manufacture of such bearing arrangements may result in quality problems.
Considering this, it is the object of the invention to provide a latch needle with a bearing arrangement that combines great precision with good wear resistance.